Secret signaling system



Patented Dec. 2, 1941 iii'efihg SECRET SKGNALING SYSTEM Donald BurkePerry,

Maplewood, N. J., assignor to American Telephone and Telegraph Company,a corporation of New York 7 Claims.

This invention relates to secret signaling systems, and particularly totelegraph systems in which the messages are encipher'ed at thetransmitting end. in order to be unintelligible, and are laterdeciphered at the receiving end in order to be rendered intelligible.

In transmitting telegraph messages by cipher it is desirable that thecipher messages be rendered unintelligible to all except authorizedreceivers. In order to accomplish this, it has heretofore been thepractice to combine the characters of the message -which in atelety'pewriter system are made up of combinations of the elements of afive-unit code-with the various combinations of a key tape. Theresultant code combinations thus make up the encip-hered andunintelligible message which is transmitted to a distant station. At thedistant or receiving station the code combinations of the unintelligiblemessage are combined in effect with the code combinations of a key tapeidentical to that employed at the sending station, and the resultantcode combinations will yield the original message in intelligible text.

Heretofore the code key tape were prepared by picking characters by lot.It has been found, however, that this process is slow. Although thesekey tapes were prepared in advance, a general use of secret telegraphsystems of this type would require many key tapes and therefore a morespeedy method to accomplish this is desired.

According to the present invention, the key tape combination to beemployed is speedily ob tained from a random The circuit arrangement ofthe invention may employ the usual type of five-unit teletypewriter codefrom which thirty-two possible code combinations are available, and thecharacters of the key tape are selected at random from the various unitsto form a suitable combination. A series of these characters punched inthe tape make up the cipher key tape such as is used in the secrettelegraph systems referred to hereinabove. The same cipher key tape willbe used in deciphering the enciphered message at the receiving station.The arrangements of this invention may, of course, be adapted to a codecombination composed of any desired number of units, 1. c. any numbergreater or less than the fiveunits referred to.

The theory of operation of this invention is based upon the employmentof a group of polar relays, one corresponding to each code unit, and

these polar relays are arranged to vibrate simulcharacters making up theselection of characters.

taneously, each at a different speed, so that during a short intervalthe various polar relays will have passed through a plurality ofcombinations of difierent contact positions. After these polar relaysare thus set into vibration,- a key or other manually-operated devicemay be pressed in order to halt the vibration of the various polarrelays. The armatures of the various polar relays will then come to reston the contacts where they happened to be positioned at the instant whenthe key or other device was pressed; that is, either on their marking orspacing contacts, as the case may be at the instant of key manipulation,By means of a distributor the relay armature positions are interpretedin terms of teletypewriter signals which may be punched in tape on areperforator for immediate use. If fiye polar relays are employed tovibrate freely simultaneously, they may make up any one of thirtytwopossible code combinations, one of which will be selected at random uponthe manipulation of the key. If the polar relays have gone throughanumber of cycles of operation, and the instant of stoppage iscontrolled manually, as is contemplated in this invention, then thecombination of units chosen is taken at random. The enciphered messageformed therefrom will be practically unintelligible except to theauthorized receivers which are supplied with the same cipher key tape.

This invention will be better understood from the detailed descriptionhereinafter following when read in connection with the accompanyingdrawing which shows one embodiment of this invention given merely forthe purpose of illustration. I

Referring to the drawing, five polar relays are shown which aredesignated A1, A2, A3, A4 and A5. Each of these polar relays includesthree windings designated W1, W2 and W3, the wind-- ing W1 beingconnected at one end to the armature ofthe relay, and at its other endto a condenser and resistor which terminates at ground, the variouscondensers being designated C1, C2, C3, C4 and C5 and the correspondingresistors R1, R2, R3, R4 and R5,. as shown in the drawing. The windingW2 of each relay is also connected at one end to its own armature, andits other end is connected to ground through another resistor, thelatter resistors being designated R6, R1,- R8, R9 and R10. The thirdwinding W3 of the various polar relays is connected at one end to itsown armature, and at its other end the winding is connected to one ofthe contacts of a relay designated 0, the various resistors beingdesigresistors Re and R1.

nated R11, R12, R13, R14 and R15, each of these resistors beingterminated in but one of the contacts of the relay 0. The armature ofeach vibrating polar relay is free to move between two contactsdesignated S and M, the S contact being the spacing contact to which thepositive terminal of a battery is connected, the negative terminal ofthe battery being grounded, the M or marking contact being likewiseconnected to a battery the positive pole of which is grounded. The M andS contacts of each vibrating polar relay are connected to a pair oflamps or other indicating devices, the lamps L1 and L2 being shown inthe drawing as connected to the S and M contacts of relay A1, the lampsL3 and L4 being similarly connected to the S and M contacts of relay A2,the remaining lamps being similarly connected to the marking and spacingcontacts of the other vibrating relays.

The armatures of the various vibrating relays A1, A2, A3, A4 and A5 arerespectively connected to the fixed respective contacts I, 2, 3, 4 and 5of a contact cam transmitter XTR of well-known construction, the lattertransmitter including also a stop contact, an auxiliary contact AUX, anda start contact designated 7. The contact 1 is connected to a source ofpositive potential, which may be provided by a suitable battery, thenegative terminal of which may be grounded. The starting magnet We ofthe contact transmitter XTR. is supplied with negative potential from asimilar battery connected to one of its terminals, the other terminal ofthe starting magnet being connected to the inner contact of a relay B.The distributor arm of the contact transmitter XTR is also connected tothe winding of a polar relay C, one terminal of which is groundedthrough suitable resistance, this polar relay being part of areperforator of well-known type, which may be also any so-called "typingreperforator.

The windings W1 and W2 of each polar relay, such as A1, for example, areused to cause the armature of the relay to vibrate. third winding W3 isemployed to cause the armature of the relay to stop in the particularposition in which it may happen to be at the instant when the thirdwinding W3 is energized. The various W3 windings are normally open atthe corresponding contacts of the relay 0.

In the case of relay A1, for example, the armature is positioned againstits marking contact M, and hence current flows, immediately after thiscontact is closed, through the winding W1 to the condenser C1 to chargethe latter condenser, the charging rate being determined by themagnitude of the resistor R1. This current is in such a direction as tohold the armature against its contact M. As the condenser becomes fullycharged, the flow of current through the winding W1 is reduced to apractical nullity. Current also flows from the source connected to thecontact M through the winding W2 of the relay A1, the latter currentbeing of a magnitude which is determined by the resistor R6. Thiscurrent is of such a magnitude as to cause the armature of the relay A1to move away from contact M and toward contact S after the chargingcurrent for condenser C1 has been effectively reduced. As the armatureleaves contact M, the condenser C1 will discharge through a circuitwhich includes both windin s W1 and W2 and This discharge current hasthe efiect of continuing the motion ofthe armature of relay A1. When thearmature of relay The upper or A1 reaches its S contact, current willthen flow from the source connected to contact S through the armature ofthe relay and the winding W1 so as to again charge the condenser C1 butin the opposite direction. As the condenser again becomes fully charged,the current through winding W1 will be reduced to a practical nullity.The current then flowing from the source connected to contact S throughthe winding W2 of relay W1 will be in such a direction and of such amagnitude as to cause the armature of relay A1 to return to its markingcontact M. And so the armature of relay A1 will vibrate between its twocontacts at a rate which is determined by the size of the condenser C1and the resistors R1 and Re.

Similarly the armatures of each of the other relays A2 to A5 willvibrate continuously between their M and S contacts. The constants ofthe various relay circuits have been so chosen that the armatures ofthese various relays will vibrate at different harmonic periods, as forexample, 4, 8, 12, 16 and 20 dots per second, or 5, 10, 15, 20 and 25dots per second, or at any other predetermined rate.

When the armature of relay A1, for example, is on its M contact, asshown in the drawing, the lamp L1 will be illuminated, current flowingfrom the sources connected to the M and S contacts in series aiding. Thecircuit established for illuminating lamp L1 will include the sourceconnected to contact M, the armature of the relay A1, the lamp L1(through appropriate resistance) and the contact S of relay A1 to whichan oppositely poled battery is connected. The lamp L2. however, will beextinguished, the armature and marking contact M of relay A1 providing ashortcircuit for the lamp L2. When the armature of relay A1 reaches itsopposite contact S, the lamp L2 will become illuminated, the current forwhich is supplied by the sources connected to the M and S contacts ofrelay A1 poled so as to be series aiding. The lamp L1, however, willbecome extinguished because of the short-circuit then provided by thearmature and spacing contact S of relay A1. Similarly the lamps L3 andL4 will become alternately illuminated as the armature of the relay A2moves between its M and S contacts, etc.

As long as the key K remains open, the relay B will be operated, currentfor which is supplied by the source connected to the auxiliary contactAUX of the transmitter XTR. Moreover, as long as the key K remains openthe various polar relays A1 to As will be simultaneously vibrating atdifierent but harmonic speeds, as already pointed out, and the two lampscontrolled by the armature of each relay will be alternately illuminatedand extinguished. The operator may determine from the continuousflashing of the lamps that his system is working satisfactorily. But assoon as the key K becomes depressed, the various armatures of the relaysA1 to As will come to rest on their previously made contacts and willremain there as long as the key K is in that position. This is becausecurrent will flow through the winding W3 of the relay A1, for example,the current in this case being supplied by the source connected to itscontact M and traversing the winding W3, the appropriate armature of therelay 0 and ground. The latter current is poled in such a direction asto maintain the armature on the contact M. Hence upon the closure of thekey K the armatures of all of the polar relays A1 to As will come torest in such positions as to illuminate the lamps L1. L3, Lain and L10,while the other lamps remain extinguished.

The contact cam transmitter XTR is shown in its stop position in whichcase the relay C of the reperforator is on its marking contact and therelay B is normally operated. Upon the closure of the key K, however,the relay will become operated, the operating current being supplied bythe source connected to the terminal common to the high resistancewindings of the relay 0. The operation of relay 0 will cause the fivearmatures at its left to close their associated contacts and thereforeground the terminals to which'the resistors R11 to R are connected. Theclosure of the outer contact at the right of relay 0 will cause thestart magnet We of the transmitter XTR to become operated, current thenflowing through the winding of the start magnet W0, and over the innercontact and armature of relay B, over the outer armature and contact atthe right of relay 0 and over key K and ground. The contact camtransmitter XTR will now start to operate.

When the transmitter XTR operates, the distributor arm of thistransmitter will then open its stop contact and its auxiliary contactAUX, in which case the relay B will then become released, the releasebeing due to the removal of current from its Winding upon the opening ofthe auxiliary contact AUX of the transmitter XTR. The release of therelay B will open the circuit of the start magnet We of the transmitterXTR due to the opening of the inner contact of the relay B. If the key Kremains closed, the relay B will remain released. In its releasedcondition the relay B will lock up the relay 0, the locking circuitbeing completed by the armature and contact at the left of relay B,current then flowing from the source connected to the right winding ofrelay 0, through that winding, over the inner contact and armature atthe right of the latter relay and the armature and contact at the leftof relay B. Moreover, the various polar relays A1 to As will remain intheir non-vibratory conditions, the armatures remaining on theirpreviously made contacts. While this is happening, the start contact Iof transmitter XTR is closed, thereby operating the polar relay C tospacing and thereby starting the reperforator. The distributor arm ofthe transmitter XTR will then close the various contacts I to 5sequentially, and the positions of the armatures of the polar relays A1to As will be registered in turn by the operation of polar relay C ofthe reperforator. Thus when the contact I of the transmitter XTR isclosed, marking battery will be supplied through the armature of relayA1 to the polar relay C; similarly marking battery will be connected tothe polar relay as the distributor arm closes contacts 2 and 3, andspacing battery will be connected to the winding of the polar relay C asthe distributor arm closes contacts 4 and 5 of transmitter XTR. Hencethe positions of the various armatures of the polar relays A1 to As willbe registered by the operation of polar relay C of the reperforator.Hence the positions of the various armatures of the polar relays A1 toAs will be registered by the operation of polar relay C of thereperforator which in turn punches the tape supplied thereto inaccordance with the corresponding characters.

When the key K is released, the distributor arm of the transmitter XTRmay have returned to its stop position, as shown in the drawing. Therelay B will then become reoperated, and the relay 0 released, asalready described. It key K is opened before the distributor arm returnsto its stop position, relay 0 will be held operated until the auxiliarycontact AUX is closed and the relay Bbecomes reoperated. Furthermore,the polar relays A1 to As will again begin to vibrate and remainvibrating simultaneously at their predetermined periods only after relay0 is released. It will be noted, however, that the figure punched on thetape by the reperforator may be read by the operator on the variouslamps L1 to L10, already referred to. The lamps may be observed by theoperator occasionally to check the random nature of the result andthereby insure satisfactory operation.

Upon the subsequent closure of the key K by the operator, the armaturesof the relays A1 to A will become closed against a diilerent combinationof, characters, as will be apparent to those skilled in the art. Thisnew combination of characters will, of course, be repunched in the tapeby the reperforator under the control of relay 0. The random characterof the apparatus is due particularly to the fact that the operator willordinarily be unable to depress the key K at regular or predeterminedintervals.

While this invention has been shown and described in certain particulararrangements merely for the purpose of illustration, it will beunderstood that the general principles of this invention may be appliedto other and widely varied embodiments without departing from the spiritof the invention and the scope of the appended claims.

What is claimed is:

1. In an electrical system, the combination of a plurality ofsimultaneously vibrating elements operated at diiierent periods, meansfor randomly stopping the vibrations of all of said elements, and meansfor progressively recording the positions of said elements after theirstoppage.

2. In an electrical system, the combination of a plurality of vibratingelements of different periods, intermittently operated means forstarting said elements in vibration and for maintaining said elements invibration, said means including means for simultaneously stopping thevibrations of said elements, and means for sequentially registering thepositions of said elements after each stoppage of said elements.

3. The combination of a plurality of vibratory elements of difierentfrequencies operating simultaneously, means for simultaneously stoppingthe vibrations of all of said elements at irregular intervals, and meansresponsive to each stoppage of said elements for progressivelyindicating the positions of said elements during each interval ofstoppage.

4. The combination of a plurality of polar relays, means for setting thearmatures of said polar relays into simultaneous vibration at differentperiods, key-controlled means for stopping the vibrations of thearmatures of said relays, and means for sequentially registering thepositions of the armatures of said relays relative to their respectivecontacts at the instant of stoppage.

5. Apparatus for preparing cipher key tape for secret telegraph systems,comprising a plurality of polar relays the armatures of which are freeto vibrate at different harmonic periods, a contact cam transmitter, akey-controlled circuit interconnecting said polar relays and saidtransmitter, means responsive to the release of said key-controlledcircuit for simultaneously vibrating the armatures of said polar relays,means responsive to the operation of said key-controlled circuit to stopthe vibrations of the armatures of said relays and to start saidtransmitter, and meansresponsiveto. the operation of said transmitter tosequentially register the positions of said armatures relative to thecontacts of said armatures.

contacts of said armatures after said armatures have stopped vibrating,and means responsive to the release of said, key-controlled circuit tore start said relay armatures in vibration; 7. The combination of aplurality of polar re- I lays, 'means for-simultaneously vibrating thearmatures of said relays at difierent'but harmonic periods, a pluralityof indicating devices two 01 6. The combination of aplura'lityi ofrelays the I armaturcs of which vibrate simultaneously at difierent butharmonic periods, a plurality of indicating devices two of which'are'associated with each relay armature to indicate which of the twocontactsof the, armature is closed by said armature, a telegraphtransmitter; 21. key-controlled,

circuit interconnecting said relays and said transmitter, meansresponsive to the operation of said key-controlled circuit for stoppingthe vibrations of the armatures of said relays and for operating thetransmitter, and means controlled by said transmitter to registersequentially thepositions of the armatures of said relays relative tothe I I I which are associated with the opposite contacts of vcontrolledby the transmitter, and means for intermittently stopping the vibrationsof the armatures of all of said relays and for starting saidtransmitter, said transmitter including means for sequentially sweepingth'e' contacts thereof in order to register at the reperforator thevarious positions ofthe armatures of said relays.

' DONALD B. PERRY.

